Change Listeners para Observable Collections

As interfaces ObservableList, ObservableMap, ObservableSet e ObservableArray fornece os métodos addListener() e removeListener() para registrar e remover listeners para notificar mudanças para coleção ou matriz subjacente.

As interfaces correspondentes ListChangeListener, MapChangeListener e SetChangeListener cada um tem o método callback onChanged() que tem os parâmetros dentro da classe Change.

A interface ArrayChangeListener tem o método callback onChanged() com parâmetros explícitos.

O exemplo mostra um programa onde um ObservableList<String> é manipulado e o objeto correspondente Change é inquirido a anexar e implementar ListChangeListener como um lambda.

package main.java.br.com.cursojavanow;

import javafx.beans.Observable;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import static javafx.collections.ListChangeListener.Change;

public class ObservableListExample {
    public static void main(String[] args) {
        ObservableList<String> strings =
                FXCollections.observableArrayList();
        strings.addListener((Observable observable) -> {
            System.out.println("\tlist invalidated");
        });

        strings.addListener((Change<? extends String> change) -> {
            System.out.println("\tstrings = " +
                    change.getList());
        });

        System.out.println("Calling add(\"First\"): ");
        strings.add("First");
        System.out.println("Calling add(0, \"Zeroth\"): ");
        strings.add(0, "Zeroth");
        System.out.println("Calling addAll(\"Second\"," +
                " \"Third\"): ");
        strings.addAll("Second", "Third");
        System.out.println("Calling set(1," +
                " \"New First\"): ");
        strings.set(1, "New First");

        final List<String> list =
                Arrays.asList("Second_1", "Second_2");

        System.out.println("Calling addAll(3, list): ");
        strings.addAll(3, list);
        System.out.println("Calling remove(2, 4): ");

        strings.remove(2, 4);
        final Iterator<String> iterator =
                strings.iterator();
        while (iterator.hasNext()) {
            final String next = iterator.next();
            if (next.contains("t")) {
                System.out.println("Calling remove()" +
                        " on iterator: ");
                iterator.remove();
            }
        }

        System.out.println("Calling removeAll(" +
                "\"Third\", \"Fourth\"): ");
        strings.removeAll("Third", "Fourth");
    }
}

package main.java.br.com.cursojavanow;

import javafx.beans.Observable;

import javafx.collections.FXCollections;

import javafx.collections.ObservableList;

import java.util.Arrays;

import java.util.Iterator;

import java.util.List;

import static javafx.collections.ListChangeListener.Change;

public class ObservableListExample {

public static void main(String[] args) {

ObservableList<String> strings =

FXCollections.observableArrayList();

strings.addListener((Observable observable) -> {

System.out.println("\tlist invalidated");

});

strings.addListener((Change<? extends String> change) -> {

System.out.println("\tstrings = " +

change.getList());

});

System.out.println("Calling add(\"First\"): ");

strings.add("First");

System.out.println("Calling add(0, \"Zeroth\"): ");

strings.add(0, "Zeroth");

System.out.println("Calling addAll(\"Second\"," +

" \"Third\"): ");

strings.addAll("Second", "Third");

System.out.println("Calling set(1," +

" \"New First\"): ");

strings.set(1, "New First");

final List<String> list =

Arrays.asList("Second_1", "Second_2");

System.out.println("Calling addAll(3, list): ");

strings.addAll(3, list);

System.out.println("Calling remove(2, 4): ");

strings.remove(2, 4);

final Iterator<String> iterator =

strings.iterator();

while (iterator.hasNext()) {

final String next = iterator.next();

if (next.contains("t")) {

System.out.println("Calling remove()" +

" on iterator: ");

iterator.remove();

}

System.out.println("Calling removeAll(" +

"\"Third\", \"Fourth\"): ");

strings.removeAll("Third", "Fourth");

}

Saída:

Calling add(“First”):

list invalidated

strings = [First]

Calling add(0, “Zeroth”):

list invalidated

strings = [Zeroth, First]

Calling addAll(“Second”, “Third”):

list invalidated

strings = [Zeroth, First, Second, Third]

Calling set(1, “New First”):

list invalidated

strings = [Zeroth, New First, Second, Third]

Calling addAll(3, list):

list invalidated

strings = [Zeroth, New First, Second, Second_1, Second_2, Third]

Calling remove(2, 4):

list invalidated

strings = [Zeroth, New First, Second_2, Third]

Calling remove() on iterator:

list invalidated

strings = [New First, Second_2, Third]

Calling remove() on iterator:

list invalidated

strings = [Second_2, Third]

Calling removeAll(“Third”, “Fourth”):

list invalidated

strings = [Second_2]

Java Code Examples

Curso Java Para Iniciantes

Fonte: The Definitive Guide to Modern Java Clients with JavaFX

Change Listeners para Observable Collections

Atualizar Pessoa da Lista

Animation

Helidon e Configuração do Ambiente

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